Lethrinus Miniatus Research Articles

DNA barcoding for the assessment of marine and coastal fish diversity from the Coast of Mozambique.

The ichthyological provinces of Mozambique are understudied hotspots of global fish diversity. In this study, we applied DNA barcoding to identify the composition of the fish fauna from the coast of Mozambique. A total of 143 species belonging to 104 genera, 59 families, and 30 orders were identified. The overall K2P distance of the COI sequences within species ranged from 0.00% to 1.51%, while interspecific distances ranged from 3.64% to 24.49%. Moreover, the study revealed 15 threatened species according to the IUCN Red List of Threatened Species, with elasmobranchs being the most represented group. Additionally, the study also uncovered four new species that were not previously recorded in this geographic area, including Boleophthalmus dussumieri, Maculabatis gerrardi, Hippocampus kelloggi, and Lethrinus miniatus. This study represents the first instance of utilizing molecular references to explore the fish fauna along the Mozambican coast. Our results indicate that DNA barcoding is a dependable technique for the identification and delineation of fish species in the waters of Mozambique. The DNA barcoding library established in this research will be an invaluable asset for advancing the understanding of fish diversity and guiding future conservation initiatives.

Spontaneous nanoemulsification of cinnamon essential oil: Formulation, characterization, and antibacterial and antibiofilm activity against fish spoilage caused by Serratia rubidaea BFMO8.

The contemporary food industry's uses of nanoemulsions (NEs) include food processing, effective nutraceutical delivery, the development of functional chemicals, and the synthesis of natural preservatives, such as phytocompounds. Although cinnamon essential oil (CEO) is widely used in the cosmetic, pharmaceutical, and food industries, it is difficult to add to aqueous-based food formulations due to its weak stability and poor water solubility. This study describes the formulation of a CEO nanoemulsion (CEONE) by spontaneous emulsification and evaluates its antibacterial and antibiofilm properties against biofilm-forming Serratia rubidaea BFMO8 isolated from spoiled emperor fish (Lethrinus miniatus). Bacteria causing spoilage in emperor fish were isolated and identified as S. rubidaea using common morphological, cultural, and 16S RNA sequencing methods, and their ability to form biofilms and their susceptibility to CEONE were assessed using biofilm-specific methods. The spontaneous emulsification formulation of CEONE was accomplished using water and Tween 20 surfactant by manipulating organic and aqueous phase interface properties and controlling particle growth by capping surfactant increases. The best emulsification, with highly stable nano-size droplets, was accomplished at 750rpm and a 1:3 ratio concentration. The stable CEONE droplet size, polydispersity index, and zeta potential values were 204.8nm, 0.115, and -6.05mV, respectively. FTIR and high-resolution liquid chromatography-mass spectrometry (HR-LCMS) analyses have revealed carboxyl, carbonyl, and phenol-like primary phytochemical functional groups in CEO and CEONE, which contribute to their antibacterial and antibiofilm properties.

First elucidation of a didymozoid life cycle: Saccularina magnacetabula n. gen. n. sp. infecting an arcid bivalve

The first first-intermediate host for a species of Didymozoidae (Trematoda: Hemiuroidea), a bivalve of the family Arcidae, is identified using multi-loci molecular data. First intermediate, (likely) third intermediate, and adult stages of a new didymozoid taxon (Saccularina magnacetabula n. gen. n. sp.) from Moreton Bay, Queensland, Australia were collected from the Sydney cockle Anadara trapezia (Deshayes) (Arcoidea: Arcidae), Sillago sp. (Sillaginidae) and Elops hawaiensis Regan (Elopiformes: Elopidae), respectively, and genetically matched. Infections in A. trapezia were present as sporocysts and cystophorous cercariae, and infected tissue at the base of the gills. Morphologically, S. magnacetabula is distinctive relative to all other didymozoids in the combination of hermaphroditism, mate-pairing, filiform body shape, the presence of a ventral sucker, a single testis, and a saccular excretory vesicle at the posterior extremity. Molecular sequence data were generated for S. magnacetabula and 42 other putative didymozoid species to explore relationships within the Didymozoidae and Hemiuroidea. In molecular phylogenetic analyses of the 28S rDNA region, the new genus forms a clade with an undescribed taxon from the redthroat emperor, Lethrinus miniatus (Bloch & Schneider) (Perciformes: Lethrinidae), from the Great Barrier Reef, and another uncharacterised taxon from E. hawaiensis. This clade is sister to a moderately well-supported clade comprising all other didymozoid species for which sequences are available, including representatives of five of the six presently recognised subfamilies. The infection of a bivalve by a didymozoid is discussed in the context of the overwhelming use of gastropod molluscs as first intermediate hosts by the Hemiuroidea.

Testing the Improvement of Coral Reef Associated Fish Distribution Models Based on Multibeam Bathymetry by Adding Seafloor Backscatter Data

Demersal fishes constitute an essential component of the continental shelf ecosystem, and a significant element of fisheries catch around the world. However, collecting distribution and abundance data of demersal fish, necessary for their conservation and management, is usually expensive and logistically complex. The increasing availability of seafloor mapping technologies has led to the opportunity to exploit the strong relationship demersal fish exhibit with seafloor morphology to model their distribution. Multibeam echo-sounder (MBES) systems are a standard method to map seafloor morphology. The amount of acoustic energy reflected by the seafloor (backscatter) is used to estimate specific characteristics of the seafloor, including acoustic hardness and roughness. MBES data including bathymetry and depth derivatives were used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Lethrinus miniatus, Loxodon macrorhinus, Lutjanus sebae, and Scomberomorus queenslandicus. The possible improvement of model accuracy by adding the seafloor backscatter was tested in three different areas of the Ningaloo Marine Park off the west coast of Australia. For the majority of species, depth was a primary variable explaining their distribution in the three study sites. Backscatter was identified to be an important variable in the models, but did not necessarily lead to a significant improvement in the demersal fish distribution models’ accuracy. Possible reasons for this include: the depth and derivatives were capturing the significant changes in the habitat, or the acoustic data collected with a high-frequency MBES were not capturing accurately relevant seafloor characteristics associated with the species distribution. The improvement in the accuracy of the models for certain species using data already available is an encouraging result, which can have a direct impact in our ability to monitor these species.

New records of anisakid nematodes from marine fishes off New Caledonia, with descriptions of five new species of Raphidascaris (Ichthyascaris) (Nematoda, Anisakidae).

Recent examinations of anisakid nematodes (Anisakidae) from marine fishes off New Caledonia, collected in the years 2003–2008, revealed the presence of the following five new species of Raphidascaris Railliet et Henry, 1915, all belonging to the subgenus Ichthyascaris Wu, 1949: Raphidascaris (Ichthyascaris) spinicauda n. sp. from the redbelly yellowtail fusilier Caesio cuning (Caesionidae, Perciformes); Raphidascaris (Ichthyascaris) fasciati n. sp. from the blacktip grouper Epinephelus fasciatus (Serranidae, Perciformes); Raphidascaris (Ichthyascaris) nudicauda n. sp. from the brushtooth lizardfish Saurida undosquamis (Synodontidae, Aulopiformes); Raphidascaris (Ichthyascaris) euani n. sp. from the Japanese large-eye bream Gymnocranius euanus (Lethrinidae, Perciformes); and Raphidascaris (Ichthyascaris) elopsis n. sp. from the Hawaiian ladyfish Elops hawaiensis (Elopidae, Elopiformes). An additional two congeneric species, R. (I.) etelidis Moravec et Justine, 2012 and R. (I.) sillagoides (Bruce, 1990) were found in the deep-water red snapper Etelis carbunculus (new host record) and the deepwater longtail red snapper Etelis coruscans (both Lutjanidae, Perciformes), and the silver sillago Sillago sihama (Sillaginidae, Perciformes) (new host and geographical records), respectively. Two unidentified congeneric species, Raphidascaris (Ichthyascaris) sp. 1 from the trumpet emperor Lethrinus miniatus (Lethrinidae, Perciformes) and Raphidascaris (Ichthyascaris) sp. 2 from the white-spotted puffer Arothron hispidus (Tetraodontidae, Tetraodontiformes) were recorded. Moreover, two species of Hysterothylacium Ward et Magath, 1917, H. alatum Moravec et Justine, 2015 and H. epinepheli (Yamaguti, 1941), were found in the leopard coralgrouper Plectropomus leopardus (type host) and the highfin grouper Epinephelus maculatus (new host) (both Serranidae, Perciformes), respectively. This is the second finding of H. epinepheli since its original description in Japan 79 years ago. Most species are described based on light and electron microscopical studies.

Levels of mercury and arsenic contamination in popular fish and shrimp brands consumed in Saudi Arabia

ABSTRACT . Fish and shrimp are public sources of healthy protein for a large fragment of the Saudi population. Therefore, the present work was conducted to assess the level of possible arsenic (As) and mercury (Hg) con­tamination of these sea foods. Eight species of fish and two species of shrimp were collected from the local mar­kets of Eastern Province, Saudi Arabia. Mercury and arsenic concentration of samples was determined by hydride generation atomic absorption spectrometry (HG-AAS). Highest average concentration of total Hg was found in Siganus canaliculatus (0.54 ± 0.06 µg/g) while the lowest level was detected in Lethrinus miniatus (0.24 ± 0.07 µg/g). For shrimp species, the levels varied from 0.13 to 0.91 µg/g for mercury and 0.19 to 0.53 µg/g for arsenic. The rank order of shrimp species based upon mercury level was Penaeus semisulcatus > Penaeus indicus ; whereas based upon arsenic level it was almost similar. Mean levels of both Hg and As in all the species studied are lower than the limits set by international health agencies; 0.550 µg/g for mercury and 6.0 µg/g for arsenic. KEY WORDS : Arabian Gulf, Fish, Shrimp, Arsenic, Mercury Bull. Chem. Soc. Ethiop. 2019 , 33(3), 573-578. DOI: https://dx.doi.org/10.4314/bcse.v33i3.17

Levels of Organotin Compounds in Selected Fish Species from the Arabian Gulf.

In the present work, data on the levels of hazardous Organotin compounds in eight commercially important fish species, caught from Arabian Gulf, has been reported. Highest levels of tributyltin (TBT) (98.5ng/g dry weight) were detected in Epinephelus Tauvina whereas minimum (43.7ng/g) were found in Acanthoparagus Bifasciatus. Highest levels of triphenyltin (TPT) were detected in Lethrinus Miniatus (107.5ng/g) whereas lowest were encountered in Acanthoparagus Bifasciatus (64.9ng/g). Highest value of total butyltin compounds (∑BT) were found in emperors (Lethrinus Miniatus) (228.4ng/g) whereas minimum was found in Acanthoparagus Bifasciatus (126.4ng/g). Similarly highest value of total phenyltin compounds (∑PT) was encountered in Epinephelus Tauvina (281.9ng/g) followed closely by Acanthoparagus Bifasciatus (281.7ng/g). In addition, the estimated daily intake (EDI) of the local population from consumption of these fish was also evaluated. Highest EDI was found to be 10.8ng/kg bw/day for epinephelus microdan. The data are also compared internationally.

Hamacreadium cribbi n. sp. (Digenea: Opecoelidae) from Lethrinus miniatus (Forster) (Perciformes: Lethrinidae) from New Caledonian waters.

A new species of Hamacreadium Linton, 1910, H. cribbi n. sp. is described from Lethrinus miniatus (Forster) from the waters off New Caledonia. It is compared with the other species of Hamacreadium reported from lethrinids and is characterised by the size of its eggs which tend to be larger [72–93 (84) vs 54–81 (56) µm long] than those of other species. Other characteristics, such as body size and shape and internal ratios, differentiate H. cribbi from other species; these differences are discussed in detail.

Assessing fine-scale diel movement patterns of an exploited coral reef fish

Understanding movement patterns of species requires that the spatial and temporal scales of experimental designs are appropriate to the proposed ecological questions. Previous research on large-scale movements of the exploited reef fish Lethrinus miniatus suggested that adult individuals may use coral reef slope habitat during the day, shifting to adjacent deeper sandy habitat at night. However, investigation of movement at a fine spatial and temporal scale is required to verify this diel activity pattern. Using a closely positioned acoustic telemetry system, movements of 11 L. miniatus were monitored among habitats from the reef crest, to reef slope and deeper adjacent sandy habitat over 3 months. Fine-scale movement patterns among these habitats were compared among four different 3 h periods of the day: dawn, day, dusk and night. Initial observations demonstrated significantly larger horizontal core areas and vertical areas of extent during crepuscular and night periods compared to during the day. Vertical space use (core area and extent) was consistently larger during dawn, dusk and night compared to during the day. Area of activity space extent within the water column and proportional overlap among areas used during different periods of the day varied among weeks, and displayed a pattern consistent with full moon periods. Although previous evidence suggested that L. miniatus adults may shift to deeper habitats adjacent to the reef slope at night, greater space use across the shallow crest to deeper sand habitat was observed during dawn, dusk and night periods. Increased luminosity during dawn, dusk and night periods may cause L. miniatus to utilise a larger search area for foraging. While further research is required to confirm foraging during the hours of twilight and darkness, this fine-scale approach identified patterns in nocturnal activity for an important reef teleost. Knowledge of these temporal and spatial differences in L. miniatus behaviour and movement are important to understanding how this species coexists within ecological niches.

Targeted demersal fish species exhibit variable responses to long-term protection from fishing at the Houtman Abrolhos Islands

Natural fluctuations in the abundance and length of targeted fish are often disrupted by acute environmental changes and anthropogenic impacts, particularly fishing pressure. Long-term assessments of targeted fish populations inside and outside areas closed to fishing are often necessary to elucidate these effects, yet few of these studies extend over long time periods. We assessed trends in the abundance and length of six targeted fish species in areas open and closed to fishing on seven occasions spanning a 9-year period (2005–2010 and 2013) at the Houtman Abrolhos Islands, Western Australia. Shallow (8–12 m) and deep (22–26 m) coral-dominated reef sites were sampled across four geographically separated island groups using baited remote underwater stereo-video (stereo-BRUV). Between 2005 and 2010, populations of Lethrinus miniatus, Lethrinus nebulosus, Plectropomus leopardus, and Chrysophrys auratus became increasingly dominated by larger individuals, potentially indicative of an ageing population. Between 2010 and 2013, however, there was a significant increase in the proportion of smaller L. miniatus, L. nebulosus, and P. leopardus in both open and closed areas, reflecting increased recruitment perhaps due to changing environmental conditions associated with a marine heat wave anomaly. This recruitment pulse was not observed for the other species in this study (Chr. auratus, Choerodon rubescens, and Glaucosoma hebraicum). Lethrinus miniatus, L. nebulosus, Chr. auratus, and P. leopardus were larger in closed areas relative to open areas; however, they were not more abundant. These complex responses to protection also varied across sampling years for certain species (e.g., P. leopardus). Monitoring changes over the long-term in areas open and closed to fishing provides a sound basis for separating environmental variability from that associated with fishing mortality, which is crucial for optimising fisheries management.

Assessing environmental correlates of fish movement on a coral reef

Variation in dispersal and movement patterns of coral reef fishes is likely linked to changes in environmental conditions. Monitoring in situ environmental parameters on coral reefs in conjunction with the movements of fishes can help explain the relationship between exploited populations and their environment. Sixty adult Lethrinus miniatus were acoustically tagged and monitored along a coral reef slope for up to 1 yr. Individuals occurred more often on the reef slope during days of cooler temperatures, suggesting a thermal tolerance threshold may exist. Results indicate that individuals responded to elevated temperatures by moving away from the reef slope to deeper adjacent habitats, thus shifting their position in the water column to remain at a preferred temperature. Space use within the water column (vertical activity space) was not influenced by environmental parameters or fish size, but this result was possibly influenced by use of deeper habitat outside the acoustic array that was not monitored. With elevation of ocean temperature, L. miniatus may need to adapt to warmer waters or disperse into cooler habitats, by either shifting their distribution deeper or towards higher latitudes. Identifying key environmental drivers that affect the distribution of reef fishes is important, and may allow managers to predict the effect of these changes on exploited species.

Sedentary or mobile? Variability in space and depth use of an exploited coral reef fish

Movement of fishes defines the distribution and abundance of populations and occurs on a range of spatial and temporal scales. To successfully parameterise assess- ments and design management strategies for exploited fish populations, knowledge and consideration of their move- ment patterns are essential. Since the efficacy of man- agement approaches vary depending on the sedentary or mobile nature of the target species, presence, space use and depth utilisation were examined to understand the move- ment patterns of redthroat emperor Lethrinus miniatus. Sixty individuals were monitored for up to 12 months in an acoustic array comprising three coral reefs, and variation in space use and movement patterns was observed among 26 individuals. Half of the individuals were recorded only in proximity of one receiver along the reef edge, while the other half were detected at multiple receivers and used horizontal areas of approximately 4 km 2 . Periods

Inferring movement patterns of a coral reef fish using oxygen and carbon isotopes in otolith carbonate

Ratios of oxygen and carbon isotopes (δ18O and δ13C) in otolith carbonate provide information on stock separation and migration of fish populations inhabiting isotopically different environments. δ18O and δ13C were analysed from Lethrinus miniatus (Forster 1801) otoliths to elucidate the probability of broad-scale movement in the Great Barrier Reef. Otolith core and edge portions were compared between and within individuals from the same cohort (n=120) to determine whether isotopically different environments were inhabited by juveniles and adults from different latitudes. A comparison between individuals revealed that δ18O and δ13C increased with latitude and were generally higher in edge than in core portions. Similarly, within most individual otoliths, δ18O and δ13C were higher in edge than in core portions. For some individuals, however, there was no difference in δ18O between core and edge portions, potentially signifying self-recruitment to the area or occupation of areas of similar chemistry. The majority of individuals from 19 to 22°S and almost half of individuals from 18°S displayed juvenile δ18O signatures characteristic of a warmer environment, suggesting movement to cooler environments or potential southerly migration of early life stages to adult habitat. In contrast, almost half of adult individuals in the most northern latitude (18°S) appeared to originate from cooler environments, suggesting movement to warmer environments or potential northward migration with ontogeny. These results infer that movement of L. miniatus individuals occurred across different isotopic environments with life stage and was related to latitude. Isotope ratios provided insight into movement patterns of L. miniatus at scales that will be important for delineating management units for this commercially important species.

Trophic ecology of large predatory reef fishes: energy pathways, trophic level, and implications for fisheries in a changing climate

Large predatory fishes are disproportionately targeted by reef fisheries, but little is known about their trophic ecology, which inhibits understanding of community dynamics and the potential effects of climate change. In this study, stable isotope analyses were used to infer trophic ecology of a guild of large predatory fishes that are targeted by fisheries on the Great Barrier Reef, Australia. Each of four focal predators (Plectropomus leopardus, Plectropomus maculatus, Lethrinus miniatus and Lutjanus carponotatus) was found to have a distinct isotopic signature in terms of δ13C and δ15N. A two-source mixing model (benthic reef-based versus pelagic) indicated that P. leopardus and L. miniatus derive the majority (72 and 62 %, respectively) of their production from planktonic sources, while P. maculatus and L. carponotatus derive the majority (89 and 74 %, respectively) of their production from benthic reef-based sources. This indicates that planktonic production is important for sustaining key species in reef fisheries and highlights the need for a whole-ecosystem approach to fisheries management. Unexpectedly, there was little isotopic niche overlap between three of four focal predators, suggesting that inter-specific competition for prey may be low or absent. δ15Nitrogen indicated that the closely related P. leopardus and P. maculatus are apex predators (trophic level > 4), while δ13C indicated that each species has a different diet and degree of trophic specialisation. In view of these divergent trophic ecologies, each of the four focal predators (and the associated fisheries) are anticipated to be differentially affected by climate-induced disturbances. Thus, the results presented herein provide a useful starting point for precautionary management of exploited predator populations in a changing climate.

Blood lactate loads of redthroat emperor Lethrinus miniatus associated with angling stress and exhaustive exercise

Baseline, post-angling and maximum attainable blood lactate concentrations were measured for the fishery species redthroat emperor Lethrinus miniatus to gain insight into the condition of fish released following c. 30 s angling and <45 s air exposure. Mean ± S.D. baseline blood lactate was 1·5 ± 0·6 mmol l⁻¹, which increased and plateaued around 6 mmol l⁻¹ at 15-30 min post-angling. These values were significantly lower than those obtained from fish maximally exhausted with a prolonged chase and air exposure protocol following capture (10·9 ± 1·8 mmol l⁻¹), suggesting that L. miniatus is not maximally exhausted during standard angling practices.

Informing the vulnerability of species to spawning aggregation fishing using commercial catch data

Fish spawning aggregations (FSAs) present a unique challenge for fishers and managers as aggregation fishing can be economically rewarding yet lead to overfishing and population collapse. Assessing the vulnerability of FSAs to fishing is often problematic due to a paucity of data. We present a tiered analysis for interrogating fishery logbook data for signals that fishing targets FSAs. We use two line fisheries that operate on Australia's Great Barrier Reef as models. The Reef Line Fishery (RLF) and Pelagic Line Fishery (PLF) operate across 9° of latitude, fishing occurs year round and the RLF has a seasonal spawning closure. A recent review reduced temporal closure days from 27 days to 10 days per year, though in the absence of any quantitative assessment of the vulnerability of targeted fish to increased harvest and hence risk. These fisheries target three reef fish groups (common coral trout Plectropomus leopardus, redthroat emperor Lethrinus miniatus, and a “other species” group mostly comprised of lethrinids and lutjanids) and a pelagic Scomberomorus commerson (narrow-barred Spanish mackerel). The tiered analyses captured the complete annual cycle of fish and fisher interaction across all latitudes and explored a number of catch metrics (landed catch, catch-per-unit-effort, and timing and size of large catch anomalies). No clear evidence of increased vulnerability of any of the three coral reef fish groups to fishing during spawning was found. Conversely the pelagic S. commerson is clearly more vulnerable to fishing during spawning. The tiered analytical approach is recommended as increased vulnerability of FSAs to fishing may not be identified by single analyses and without relative comparisons among species, the most vulnerable may be overlooked.

Cucullanid nematodes (Nematoda: Cucullanidae) from deep-sea marine fishes off New Caledonia, including Dichelyne etelidis n. sp.

Three nematode species of the family Cucullanidae, intestinal parasites of marine perciform fishes, are reported from off New Caledonia: Cucullanus bourdini Petter & Le Bel, 1992 from the crimson jobfish Pristipomoides filamentosus (Valenciennes) and the goldflag jobfish Pristipomoides auricilla (Jordan, Evermann & Tanaka) (new host record) (both Lutjanidae); Dichelyne etelidis n. sp. from the deep-water red snapper Etelis carbunculus Cuvier (type-host) and the deep-water longtail red snapper Etelis coruscans Valenciennes (both Lutjanidae); and Dichelyne sp. (only one female) from the trumpet emperor Lethrinus miniatus (Forster) (Lethrinidae). Detailed light and electron microscopical studies revealed in C. bourdini some taxonomically important, previously unreported features, such as the location of the excretory pore, nature of the vulva and the size of fully-developed eggs. The new species, D. etelidis, is characterised mainly by the length of the spicules (462-748 μm), a single intestinal caecum, the location of the deirids and excretory pore, the arrangement of the genital papillae and the host group.

An annotated list of fish parasites (Copepoda, Monogenea, Digenea, Cestoda and Nematoda) collected from Emperors and Emperor Bream (Lethrinidae) in New Caledonia further highlights parasite biodiversity estimates on coral reef fish

Parasites were collected from 17 species of emperors and emperor bream (Lethrinidae) in the waters off New Caledonia, South Pacific. Host-parasite and parasite-hosts lists are provided, with a total of 188 host-parasite combinations (11 per fish species), including 81 identifications at the species level. A total of 52 parasites were identified at the species level, and 40 new host records were found. Results are presented for larval isopods, copepods (16 species), monogeneans (24), digeneans (27), cestodes (11) and nematodes (10). When results were restricted to the four best-sampled fish species for which more than 30 specimens were examined, the number of host-parasite combinations was 22.25 per fish species, and the number of parasite taxa identified at the species level was 9.5 per fish species. From these data, the total number of metazoan parasite species predicted from all lethrinid species of New Caledonia, based on a classification of fish sizes using length in three categories, is 340, i.e. 13 per fish species. A biogeographical comparison with Heron Island on the Great Barrier Reef (Queensland, Australia) was possible only for a single fish species, Lethrinus miniatus: in a total of 65 host-parasite combinations, only five taxa identified at the species level (three monogeneans and two digeneans) were shared at both localities. Parasite biodiversity in lethrinids was of similar magnitude to that in groupers (Serranidae Epinephelinae) in the same area, and this study confirms a previous prediction of 10 parasite species per coral reef fish species. Although this study required significant sampling and identification, we estimate that only 13% of the parasites of lethrinids are known in New Caledonia.

Large decline in the abundance of a targeted tropical lethrinid in areas open and closed to fishing

In Western Australia, one of the most important commercially and recreationally tar- geted, yet understudied fish species is the redthroat emperor Lethrinus miniatus. The present study aimed to compare the relative abundance and size of L. miniatus in areas open and closed to fishing at the Houtman Abrolhos Islands and to assess change in these populations over a 5 yr period. Baited remote underwater stereo-video systems (stereo BRUVs) were used to conduct the surveys from 2005 to 2009, which included different depths and locations across 4 geographically separated groups of islands. Data showed high spatial variability in the relative abundance of L. miniatus across depths, sites, and island group locations. In 2005 and 2006, L. miniatus were more abundant at depths of 22 to 26 m than in 8 to 12 m. At this time, individuals were also 1.3× more abundant and 10% larger in length in areas closed to fishing than in areas open to fishing. Starting in 2007, however, relative abundances of L. miniatus declined so markedly that in 2009 only 20% of the 2005 and 2006 numbers remained. This decline removed the disparity between depths, closed areas and fished locations. Unlike with relative abundance, L. miniatus remained consistently larger inside closed areas (mean 370 mm fork length) than in areas open to fishing (mean 350 mm). Of the 483 individuals measured across the 5 yr of the study, 98% were larger than the minimum legal size for retention, and therefore subject to harvest. Mean lengths increased each year, as the size structure of the population reflected an aging cohort. With declines in measured relative abundance in excess of 80% over the past 5 yr, the sustainability of L. miniatus assemblages at the Houtman Abrolhos Islands is in question.

Exploring movement patterns of an exploited coral reef fish when tagging data are limited

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 405:87-99 (2010) - DOI: https://doi.org/10.3354/meps08527 Exploring movement patterns of an exploited coral reef fish when tagging data are limited Ashley J. Williams1,2,*, L. Richard Little3, André E. Punt3,4, Bruce D. Mapstone3, Campbell R. Davies3, Michelle R. Heupel5 1Fishing and Fisheries Research Centre, School of Earth and Environment Studies, James Cook University, Townsville, 4811 Queensland, Australia 2Oceanic Fisheries Programme, Secretariat of the Pacific Community, BP D5, 98848 Noumea, New Caledonia 3CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, 7001 Tasmania, Australia 4School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195-5020, USA 5School of Earth and Environmental Sciences, James Cook University, Townsville, 4811 Queensland, Australia *Email: ashleyw@spc.int ABSTRACT: Movement is one of the most fundamental demographic variables affecting the distribution and abundance of populations, but movement patterns for exploited populations of coral reef fish have not been studied extensively. Obtaining movement data for many species by means of traditional tagging methods can be difficult because of high tagging-induced mortality and low recapture rates. We used an age-structured population dynamics model parameterised using data from different regions to explore potential movement patterns for the red throat emperor Lethrinus miniatus, an exploited coral reef fish species for which traditional tagging studies have been unsuccessful. The model used a Gaussian function to describe the proportion of fish of a given age moving to or from 1 of 3 regions (Townsville, Mackay and Storm Cay) of the Great Barrier Reef. The model was fitted with and without movement to empirical age frequency data from each region over a 5 yr period (1995 to 1999). Including movement in the model led to significantly better fits to the data and revealed discrete movement patterns within each region. The model predicted net immigration to the Townsville region and net emigration from the Mackay and Storm Cay regions. We present alternative hypotheses about migration patterns of L. miniatus and highlight the importance of determining the scales at which movement in larger, exploited coral reef fishes occurs. KEY WORDS: Movement · Coral reef fish · Lethrinus miniatus · Great Barrier Reef · Modelling · Migration · Fisheries Full text in pdf format PreviousNextCite this article as: Williams AJ, Little LR, Punt AE, Mapstone BD, Davies CR, Heupel MR (2010) Exploring movement patterns of an exploited coral reef fish when tagging data are limited. Mar Ecol Prog Ser 405:87-99. https://doi.org/10.3354/meps08527 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 405. Online publication date: April 29, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.